Process for vulcanizing rubber and similar materials and products obtained thereby



Patented Sept. 8, 1925.

UNITED STATES PATENT OFFICE.

SIDNEY I. CADWELL, OF LEONIA, NEW" JERSEY, ASSIGNOB TO THE NAUGATUQK CHEMICAL COMPANY, OF NAUGATUCK, CONNECTICUT, A CORPORATION OF CON- raocnss iron vuncamzmo ncnnnn Ann SIMILAR maraamLs AND rnonuc'rs on'raman 'rnnnnBY.

No Drawing.

To all whom it may concern:

Be it known that I, SIDNEY M. GAnwEnL, a citizen of the United States, residing in Leonia, county of Bergen, State of New Jersey, have invented certain new and useful Improvements in Processes for Vul-v canizing Rubber and Similar Materials and Products Obtained Thereby, of which the following is a full, clear,-and exact description.

This invention relates to vulcani zing rub--.

her and similar materials and products obtained thereby. I

This application 'is a continuation 1n part of my copending application Serial No. 548,829, filed A ril 1, 1922.

'The principa object of the present-1nvention is to provide a relatlvely inexpensive material which may be used with oxides of lead to accelerate the vulcanization of rubber, particularly litharge as it is emplo ed in so-c'alled mechanical rubber goods, which usually contain rather large amounts of compounding ingredients.

The invention accordingly comprises a process of vulc'auizing rubber or similar material which includes combining rubber with sulphur, lead dithiobenzoate and an oxide of lead, and vulcanizing the rubber.

In carrying out the invention in its preferred form, 100 parts of rubber, 5 parts oflitharge, 3 parts of sulphur and fl parts of a mixture of 1 part of lead dithiobenzoate and 63 parts of a clay (mineral flour).

suitable for rubber compounding or similar rubber filler are nixed by milling in the usual manner. This compound is then vulcanized for minutes at approximately 286 F. vulcanization temperatures within the normal range of hot vulcanization temperature, above 240 F. ma be employed;

Lead dithiobenzoate may e repared by the method of J. Houben escribed in Berichte der Deutscher Ghemischen Gesellschatt, vol. 39, page 3219 with the modification that acetic acid is employed to neutralize the excess of sodium bicarbonate in the aqueous aolution of sodium-dithiobenzoate Application filed November '22, 1923. Serial No. 676,353.

- preparedaccording to the procedure of Houben. The lead dithiobenzoate is then precipitated by treating the solution with an aqueous solution of lead acetate. .Lead dithiobenzoate is a stable chemical. The mixture of this material with clay or similar compounding ingredient may be carried out in any desired manner.

The vulcanization process described above is more rapid and the-vulcanizate secured in accordance therewith is of better quality the rubber.- T

2. A process of vulcanizing rubber or similar material which comprises combining' "rubber with sulphur, lead dith'iobenzoate, li-tharge and a filler, and vulcanizing the rubber at. normal hot vulcanization temperature.

3. A process'of vulcanizing rubber or similar material whichcomprises combining with rubber approximately 3 parts by weight of sulphur, 4' arts by weight of a mixture of 1 part. 0; lead dithiobenzoate and 63 parts of clay, 5 parts by weight of lith'arge, andvulcanizing the rubber.

4. Vulcanized rubber derived from rub- I ber combined with sulphur, lead dithiobenzoate and litharge;

5. Vulcanized rubber derived from rub ber combined with sul hur, lead dithiobenzoate, litharge and a ller.

Signed at New York, county and State of New York, this 20thday of November.

SIDNEY M. CADWELL. 

